1. Field
This disclosure relates generally to semiconductor processing, and more particularly, to vias between conductive layers
2. Related Art
Vias are used for providing electrical connection between two different conductive layers. With the number of transistors that are now present on integrated circuits, the number of vias can exceed a billion and there can be ten different conductive layers. Even if each via is highly reliable, there are so many vias that it is likely for there to be at least one via failure. This has lead to widespread use of redundant vias in which there are at least two vias for a given electrical connection between conductive layers so even if one via fails, there will still be an electrical connection through the other via. In most cases this can be achieved without increasing the area of the integrated circuit. There are via locations, however, where adding a redundant via would require increasing the area. In such a case there is a tradeoff between a risk of via failure and increasing the area. For the case where the decision is to risk via failure, it is important the vias with no redundant via be reliable.
Accordingly, it is desirable to provide a technique for improving the reliability of vias that do not include a redundant via.